The invention discloses a method for preparing linear positive temperature coefficient (PTC) thermistor slurry. The method comprises the following steps: 1. mixing copper hydroxide, ruthenium dioxide according to a certain mol ratio, performing ball milling, drying, crushing, sieving, sintering, crushing, and performing ball milling to obtain functional ceramic phase particles for later use; 2. mixing silica, alumina, boron trioxide, barium oxide and titanium dioxide according to a certain mass ratio, performing ball milling, drying, crushing, sintering, quenching, performing ball milling to obtain glass powder for later use; 3. mixing the resultants from the former two steps with copper oxide in a certain ratio and adding a certain amount of an organic carrier to roll into slurry. According to the invention, not only the linear PTC thick film slurry for screen printing can be developed, but also the slurry with high temperature coefficient of resistance (TCR) and high square resistance is obtained, wherein the TCR is more than 4000ppm/DEG C and the square resistance is more than 100 omega per square.